I considered making a new TAS of this game, since the current publication is a couple of years old. I realized that I will not have time to work on such a project.
However, I've spotted some improvements I'd like to share.
Here is the first scene completed 28 frames faster.
http://dehacked.2y.net/microstorage.php/info/327562682/DD%20Level%201.fm2
Here are the Chins in level 3 completed AT LEAST 150 frames faster. This movie was started from a save point in Phil's movie, and I only used slow motion (not frame advance) to do this scene.
http://dehacked.2y.net/microstorage.php/info/66234923/dd-chin.fm2
Finally, this last movie was also taken from a savepoint in Phil's movie, but it is unknown if it could save time. Due to this positioning Phil had, it wouldn't save time in his movie, but you can jump in the water on the first frame that the 'advance' hand appears.
http://dehacked.2y.net/microstorage.php/info/624930915/dd-water.fm2
I also have a feeling that the final room in Mission 3 can be improved, but I haven't greatly tested it.
Anyway, all of you "Skilled" and "Expert" players take a look at this and share some thoughts. Note that due to randomness, it may be possible that all of these may not be able to be used in the same movie. For example, I extended the first movie a bit, but lost 8 frames on the Lindas in level 1 compared to Phil.